Tuning assembly



Patented Apr. 24, 1951 TUNING ASSEMBLY Merlin Petroli, Lake Bluff, Ill.,

assignor to Stewart-Warner Corporation, Chicago, Ill., a corporation of Virginia Application September 3,

Claims.

The vpresent invention relates generally to high frequency inductance tuning devices and more particularly to a new and improved tuning assembly utilizing the inherent qualities of the inductometer circuit.

One of the principal objects of the invention is to provide a tuning device ofsimple design and low cost construction.

Another object is to provide a tuning device which may be quickly and easily adjusted and which is provided with a minimum of moving parts.

A further object is to provide a tuner having little loss due to stray magnetic fields and of substantially xed low capacity.

Further objects and advantages will become apparent from the ensuing description of one embodiment of the invention.

In the drawings:

Fig. 1 'is an isometric view of the complete tuning assembly unit;

Fig. 2 is a vertical sectional view of the unit taken on the line 2-2 of Fig. 3;

Fig. 3 is a vertical sectional view taken on line 3-3 of Fig. 2;

Fig. 4 is a fragmentary sectional view showing the rotating element of the tuning assembly taken on the line 4 4 of Fig; 3 ;k

Fig. 5 is a plan View of the contactor shown applied to a section of the rotating element;

Fig. 6 is an elevational view of the contacto:` shown applied to a section of the rotating element;

Fig. 7 is a schematic representation of the electrical connection of the coils of the tuning assembly; and

Fig. 8 is a schematic wiring diagram illustrating a modied form of coupling.

In this tuning assembly the basic elements are shown in Fig. 1 as a rotating disk I0, a stationary platey I2, a bail I4 used to rotate the disk Hl, and a contact I6. The contact I6 is more clearly shown in Figs. 5 and 6.

The disk I0 is attached securely to the rotatable bail I4 by Vsmall'ilaps I8 stamped from the bail I4 and secured by rivets to the disk I0 as is clearly shown in Figs. 2', 3 and 4. The disk ID is circular in shape and made of a suitable type of nonconducting plastic, such as polystyrene. On one side of the disk I0 is a half turn of an inductance coil which is either embossed, printed or electroplated on the disk Il) and consists of a conductive material such as silver. One end of the coil 2|) is electrically connected to the rotating bail I4 at 23 and the other 1948, Serial N0. 47,573 (Cl. 171-242) end terminates at a conducting surface 2| as is clearly shown in Fig. 4. Over this surface 2| is mounted the contactor I6 as shown in Fig. 6. The contacter I6 has arms 22 which extend through suitable slots in the disk l0 and are bent toward each other to bring the contact piece 24 into electrical connection with the contact surface 2| on the disk I0.

The contact I6 has mounted on it a rivet 26 formed of suitable contact material such as silver and is in contact with a contact surface 25 on the stationary plate I2 similar to the contactl surface 2| on the disk I0. This contact surface 25 is at one end of a half turn of an inductance coil 28 (Fig. 2) which is of the same type as coil 20 and which terminates in a soldering lug 30 for connection to the leads of a tuning circuit. The plate l2 is formed of a polystyrene-like material and on its other side is printed, or otherwise formed, a coil 32 as shown in Fig. 2. This coil 32 is positioned in axial alignment with the coil 28 and is almost a complete loop. The two ends of this coil are terminated by lugs 34 and 36 which serve to connect this coil to an electrical network. Rods 38 and 40 of nonconductive material are used to support the plate |2 in its stationary position between end supports 42 and 44.

The electrically conductive end supports 42, 44 are about the same shape as the stationary plates I2. Support 44 has mounted in it a pin 46 (Fig, 3). The pin 46 is securely attached to the bail I4 and is rotatable in a bushing 48 mounted in the support 44. A washer 5|) keeps the bail I4 away from the support 44.

The movable bail I4 carrying the disks ID is rotated by a nonconductive tuning shaft 52 which rotates in the support 42 and is rigidly fixed to the bail I4. The shaft 52 extends only through the support 42 and is used to rotate the bail I I and thereby change the position of the disks Ill. Due to the construction of the support 42 the arm I4 can be rotated only in a degree arc. The conductive bail |4 is electrically connected to the conductive grounded support 42 by a conductive pigtail 54.

There can be as many groups of the combination of a disk IU and a plate I2 as is needed for the circuit requirements, and in Fig. 1 two such combinations are shown. As indicated schematically in Fig. 7 the electrical circuit for one such combination would be from lug 30 through the coil 28 to the contact 26 in contactor I6, from the contact surface 24 to the Contact surface 2|, through the coil 20 to the rotating bail lll, from the rotating bail I4 to the pigtail 54 and to ground through the support 42. Inductively coupled to the series combination of the coil 28 and the coil 20 is the stationary coil 32. All of these coils are in close proximity to one another so that most of the flux in any one coil will link the other two. Thus, a close coupling will be effected, but not so close as to cause two resonant peaks in the rotating coils when they are connected in a tank circuit.

A typical operation of the tuning assembly would be to use the stationary coil 32 as an antenna pick-up coil on an FM receiver. The relatively rotating coils 28 and 20 would be the secondary of the input transformer, of which coil 32 is the primary, and would be connected to a capacitance thereby forming a tuned tank circuit. In the position of the members as shown the maximum amount of flux from coil 32 would linlr` the secondary coils and the greatest inductance will be created in these coils. As rotation in either direction is caused the inductance will decrease due to the fact that less lines of flux can link the coils and a greater selfinductance is set up in the coils to oppose the induced inductance.

Coupling to the variable inductance may also be accomplished in the manner shown in Fig. 8, wherein a conductor i leading to the next stage is connected to a fixed t-ap 43 on coil 28 through a small series condenser 44, thus making the use of the coil 32 unnecessary.

While I have shown and described a preferred embodiment of my invention, it will be apparent that numerous variations and modifications thereof may be made without departing from the underlying principles of the invention. I therefore desire, by the following claims, to include within the scope of the invention all such variations and modifications by which substantially the results of my invention may be obtained through the use of substantially the same or equivalent means.

I claim.

l. A tuning assembly, comprising a stationary plate, a rotating plate, a layer of conducting Inaterial on one side of the stationary plate in the form of a single turn of a coil, a layer of conducting material on the other side of the stationary plate in the form of a one-half turn of a coil, a layer of conducting material in the form of a one-half turn of a coil on the rotating plate, the rotating plate being arranged parallel to and closely adjacent the stationary plate, an electrical contact between one end of the onehalf turn coil on the rotating plate and one end of the one-half turn coil on the stationary plate, a movable bail connected to the rotating plate, means forming an electrical connection between the other end of the one-half turn coil and the bail, and means for selectively positioning the movable bail with respect to the stationary plate.

2. A timing assembly comprising a stationary plate, a rotating plate, a layer of conducting materia-l on one side of the stationary plate in the form of a single turn of a coil, a layer or" conducting material on the other side of the stationary plate in the form of a one-half turn oi a coil, a layer of conducting material in the form of a one-half turn of a coil on the rotating plate, the rotating plate being arranged parallel and closely adjacent to the stationary plate,

-s one end of the one-half turn means electrically connecting one end of the one-half turn coil on the rotating plate and one end of the one-half turn coil on the stationary plate, a movable bail connected to the rotating `plate, means forming an electrical connection between the other end of the one-half turn coil and the bail, and means for selectively positioning the movable bail with respect to the stationary plate.

3. A tuning assembly, comprising a stationary plate, a rotating plate, a layer of conducting material on one side of the stationary plate in the form of a single turn of a coil, a layer of conducting material on the other side of the stationary plate in the form of a one-half turn of a coil, a layer of conducting material in the form of a one-half turn of a coil on the rotating plate, the rotating plate being arranged parallel to and closely adjacent the stationary plate, a movable electrical contact between one end of the one-half turn coil on the rotating plate and one end of the one-half turn coil on the stationary plate, a movable bail connected to the rotating plate, means grounding the other end of the movable one-half turn coil, and means for selectively positioning the movable bail with respect to the stationary plate.

4. A tuning assembly, comprising a stationary plate, a rotating plate, a layer of conducting material on one side of the stationary plate in the form of a single turn of a coil, a layer of conducting material on the other side of the stationary plate in the form of a one-half turn of a coil, a layer of conducting material in the form of a one-half turn of a coil on the rotating plate, the rotating plate being arranged parallel to and closely adjacent the stationary plate, a movable electrical contact between one end of the one-half turn coil on the rotating plate and coil on the stationary plate, and means for variably positioning the rotating plate with respect to the stationary plate.

5. A tuning assembly, comprising a plurality of pairs of plates, each pair consisting of a stationary plate, a rotating plate, a la-yer of conducting material on one side of the stationary plate in the form of a single turn of a coil, a layer of conducting material on the other side of the stationary plate in the form of a one-half turn of a coil, a layer of conducting material in the form of a one-half turn of a coil on the rotating plate, the rotating plate being arranged parallel to and closely adjacent the stationary plate, means electrically connecting one end of the one-half turn coil on the rotating plate and one end of the one-half turn coil on the stationary plate, a movable member connected to the rotating plate, means forming an electrical connection between the other end of the onehalf turn coil and the movable member, and means for selectively positioning the movable member with respect to the stationary plate.

MERLIN PET ROFF.

REFERENCES CITED The following references are of record in the file of this patent: 

